1. Field of the Invention
This invention relates to an analog meter of light emitting type in which letters, a dial, a pointer and the like may look such that they emit light therefrom, and more particularly to a display apparatus suitable for use with an analog meter for a vehicle.
2. Description of the Prior Art
An exemplary one of such analog meter of light emitting type is shown in FIG. 14.
This type of meter includes a meter mechanism 41, a dial 42, and a light introducing plate 43 interposed between the meter mechanism 41 and the dial 42. Thus, light from a light source bulb 44 is introduced into the light introducing plate 43 by way of ends 43a thereof so as to cause the light introducing plate 43 to emit light to a back face of the dial 42 so that a transmitting graduated portion and so forth formed on the dial 42 may look such that they emit light therefrom. The pointer 45 also may look such that it emits light therefrom by introducing light, which is introduced from the light introducing plate 43 to a boss 45a of the pointer 45 through periphery of a pointer shaft 41a, into the pointer 45 and dispersing the light in the pointer 45.
Meanwhile, in daytime during operation, when intense light such as sun light is introduced from a windshield into a driver's seat of an automobile or immediately after an automobile enters a tunnel, changing in amount of external light causes a drivers' eyes to be dazzled because irises of the driver become small, which reduces visibility of the display since overall meter looks dark. In order to prevent the poor visibility, it is considered that luminance of the display pattern should be increased. However, in the conventional display apparatus for a vehicle with the light emitting analog meter described above, since the introducing plate is used for indirectly emitting light on back face of the dial, small luminance of the display pattern and unevenness in the luminance makes it difficult to solve the problem.
Therefore, in Japanese Patent Application No. Heisei 1-321496, the applicant has already proposed an analog meter of light emitting type with high luminance which is provided with a discharge lamp and a reflector as a light source to display graduations, letters, a pointer, and the like without uneven luminance and to keep the luminance at high level. This display apparatus for a vehicle is outlined in FIG. 11. As described in cross-sectional view of the figure, the display apparatus includes a circular pointer plate 18 having a light transmitting slit on the front surface thereof and a dial 17 behind the rear surface thereof. Portions of the dial 17 for graduations and numerals are void and a circular portion where these portions overlap with the pointer plate 18 is formed to permit light to transmit therefrom. Other portions are formed to have black face.
Further, the dial 17 is provided with a light dispersion plate 16 on the rear face thereof and is further provided with a reflector 13 behind the light dispersion plate. A semi-cylindrical concave reflecting portion of the reflector 13 is directed to the dial 17 side, and a cylindrical discharge lamp 14 having a shape of cylinder is disposed along a focus of the reflector 13. Behind the reflector 13 is disposed a mechanism 11 (movement). The mechanism rotates the pointer shaft 11a according to electrical signals from an electrical circuit not shown to rotate the pointer plate 18 fixed to an end of the pointer shaft 11a.
As shown in FIG. 11, the display apparatus for a vehicle described above has a distance d, which requires a relatively large space for accommodating the apparatus in the vehicle. Moreover, it may be difficult for some vehicles to accommodate the apparatus therein. As shown in FIG. 12, when a reflector 13' having a concave portion at the center thereof, the mechanism 11 can be accommodated in the concave portion so that the distance d can be shortened. However, it becomes necessary to dispose the discharge lamps 14 at both sides, as shown in FIGS. 12, and 13, which causes areas m to be bright and an area n dark. On the other hand, when dispersion effect is improved to prevent unevenness in the luminance, overall luminance will be decreased.